bookmarklet

A "bookmarklet" is a little javascript (really Ecmascript) program that is stored in the URL slot of your browser's bookmarks. It has a protocol-specifier of "javascript:" rather than the usual "http:". You can convert a piece of javascript into a one-line form for use as a bookmarklet here: http://spruce.flint.umich.edu/~jalarie/jaa_kcd2.htm

When you click on the bookmark, the program executes.

Bookmarklets were first suggested by the Netscape Developer Guide back in 1997 which proposed a method for "Activating JavaScript Commands From the Personal Toolbar", and offered a simple example to open a new window:

javascript:void(window.open(""))

You can put any javascript into a bookmarklet and hence automate most browser functions. You can go to a new page, look at hi-lighted text, show "hidden" parts of a webpage (like comments and stylesheet info), or move windows around, all at the touch of a button. There are slight variations in the javascript support in Netscape-type browsers (including those based on Mozilla) and Internet Explorer so not every bookmarklet will work in every browser.

The bookmarklet approach has been used by noders, see these fine nodes for some e2-centric examples: